Our published European application (0278648A2) describes an aerial optical fibre cable in which a surface-slotted dielectric core acts as the strength member and the armouring and houses a ribbon optical fibre element. The slot is filled with a soft thixotropic water blocking gel and the slot is closed and sealed with a close-fitting cap which is bound in position with a yarn. The core is then driven several times around a capstan with the cap facing outward to induce an excess length of ribbon element in the core when it leaves the capstan. Plastics material is then extruded over the core to provide a tight-fitting sheath.
This cable construction provides strain relief for the ribbon optical fibre element by ensuring that the element inside the core is longer than the cable so that when the cable is put under tension and the core stretches, the element is not put under tension.
It is an object of the present invention to provide an improved cable in which the strain relief of the optical fibre ribbon element is improved.